1. Technical Field
The present invention relates to a liquid crystal device having a touch key function and an electronic apparatus including the liquid crystal device.
2. Related Art
In such a liquid crystal device, beads are distributed between a TFT array substrate and an opposing substrate with a liquid crystal layer interposed in between in order to maintain a constant distance (so called, an inter-substrate gap) between the substrates. There is the probability that such beads bring problems such as contrast degradation of the liquid crystal device and degradation of display performance of the liquid crystal device. In particular, in a lateral electric field type liquid crystal device controlling alignment of liquid crystals by a lateral electric field applied along the surface of the TFT array substrate, the contrast degradation is significant. There are known liquid crystal devices maintaining the constant inter-substrate gap by using spacers each having a pillar form, disposed between the TFT array substrate and the opposing substrate, in order to suppress such contrast deterioration. The spacers having a pillar form can be formed by performing light-exposure processing with respect to a positive type photosensitive material, such as acryl or polyimide (for example, JP-A-10-82909 and JP-A-6-175133). Further, JP-A-2002-333630 discloses a liquid crystal device using spacers which are buried in a sealing member allowing a pair of substrate to be bonded to each other and which have high rigidity coefficient.
On the other hand, as for such a kind of liquid crystal devices, there is known a liquid crystal device having a touch key function which checks whether input means such as a finger presses a displaying surface of the liquid crystal device by detecting the change of capacitance between the TFT array substrate and the opposing substrate, which is generated when the input means such as a finger presses the displaying surface, and which can enable the input of various information.
However, in such a kind of liquid crystal device, it is technically difficult to form spacers having a uniform size using a photolithography technique so there is a technical problem in that the size variation of the spacers occurs. In addition, there is the probability that the liquid crystal device contracts when environment, such as ambient temperature at which the liquid crystal device is used, changes and thus it is difficult to maintain the uniform inter-substrate gap in such a case.
Further, there is a problem in that size of resin patterns to be turned into spacers before exposure must be larger than size of the spacers so the spacers can be stably formed when simultaneously forming a plurality of spacers using a photolithography process. There is still a further problem in that an aperture ratio is lowered according to the sizes of the spacers as the aspect ration of the spacers becomes lower. Here, if the aperture ratio is raised by reducing the size of spacers, the strength of the spacers becomes insufficient, and thus the inter-substrate gap cannot be maintained by the spacers. If density of the spacers on the substrate is increased on purpose to supplement insufficiency of the strength of the spacers, the number of exposure processes is increased, and thus the manufacturing process of the liquid crystal device becomes complex.
In the liquid crystal device having a touch key function, input of a variety of kinds of information can be accomplished by detecting the change of capacitance between the TFT array substrate and the opposing substrate, which is generated when the opposing substrate is pressed. However, there can be a problem with the liquid crystal device having the touch key function in that if the opposing substrate is in contact with the TFT array substrate, the substrates are short-circuited, and thus the capacitance cannot be detected.